This commit takes some of the work done on the SPI class from #8445, and
refines it, to provide the per-peripheral mutex functionality.
This also implements GPIO-based SSEL, which exposes a new
select()/deselect() API for users to group transfers, and should work on
every platform (unlike the HAL-based SSEL). This requires users to use a
new constructor to avoid backwards compatibility issues.
To activate the per-peripheral mutex, the HAL must define SPI_COUNT and
provide spi_get_peripheral_name(). (In #8445 this is a reworked
spi_get_module, but the name is changed here to avoid a collision with
existing HALs - this commit is designed to work without wider HAL
changes).
Fixes: #9149
For keep supporting external APIs with the same name (supposedly there are a larger
number of users of those APIs), BufferedSerial and ATParser are being renamed.
BufferedSerial becomes UARTSerial, will complement a future USBSerial etc.
ATParser becomes ATCmdParser.
* UARTSerial moves to /drivers
* APN_db.h is moved from platform to cellular/util/.
* Original CellularInterface is restored for backward compatability (again, supposedly there
are users of that).
* A new file, CellularBase is added which will now servce as the base class for all
upcoming drivers.
* Special restructuring for the driver has been undertaken. This makes a clear cut distinction
between an on-board or an off-board implementation.
- PPPCellularInterface is a generic network interface that works with a generic FileHandle
and PPP. A derived class is needed to pass that FileHandle.
- PPPCellularInterface provides some base functionality like network registration, AT setup,
PPP connection etc. Lower level job is delegated to the derived classes and various modem
specific APIs are provided which are supposed to be overridden.
- UARTCellularInterface is derived from PPPCellularInterface. It constructs a FileHandle and
passes it back to PPPCellularInterface as well as provides modem hangupf functionality.
In future we could proive a USBInterface that would derive from PPPCellularInterface and could
pass the FileHandle back.
- OnboardCellularInterface is derived from UARTCellularInterfae and provides hooks to
the target provided implementation of onbard_modem_api.h. An off-board modem, i.e, a modem on
a shield has to override the modem_init(), modem_power_up() etc as it cannot use
onboard_modem_api.h.
Kevin Bracey
Hasnain Virk